Oil spill recovery and clean-up presents many major problems. A substantial portion of crude oils that are spilled on the sea readily form water-in-oil emulsions due to the mixing energy supplied by the wave action of the sea, and the presence of surfactants and bi-wettable particulates naturally present in the crude. These surfactants and particulates prevent coalescence of the water droplets trapped in the oil, such that a particularly sticky and viscous emulsion is formed which is considerably more difficult to handle than plain crude oil. This emulsion may contain as much trapped water as four times the oil, severly straining clean-up and storage facilities at sea.
Clean-up and storage facilities at sea are typically barges and floating dracones, which are large, sausage-shaped rubber containers. The cost of storing recovered crude on these on-scene storage facilities is presently approximately $100/bbl. Obviously, an emulsion containing as much as 80% water would be very wasteful of storage space and money, and would make recovery of the crude oil impractical.
In an attempt to resolve this problem, various demulsifiers have been injected into the water/crude oil emulsion to separate out the water prior to storage at sea.
Unfortunately, presently available demulsifiers have many shortcomings and disadvantages, to wit: (a) Removal of the water from the water/crude oil emulsion is not always complete, leaving the problem of environmentally disposing of oil-containing water residues at sea; (b) many demulsifiers are toxic to the environment, traces of which are left behind in the discarded water residues; (c) many demulsifiers require huge amounts of mixing energy, and take a long time to accomplish the separation of the water from the crude; and (d) most demulsifiers are effective with only selective types of crude oils, and may not be effective in every case or situation.
The present invention seeks to provide a demulsifier which will eliminate or resolve most, if not all, of the aforementioned disadvantages of these prior demulsifiers, and which will further provide many new and useful advantages, as will be explained hereinafter.
In addition, it is believed that this is the first time any one has composed a demulsifier for water/crude oil emulsions comprising a mixture of (1) at least one wetting agent formulated to displace one liquid from the surface of a bi-wetted solid disposed at a boundary of a water droplet and oil phase continuum with another liquid via a reduction of the liquid-solid interfacial tension, and (2) at least one surfactant effective in displacing an indigenous emulsifying surfactant film and which permits aqueous droplet coalescence and separation from the oil phase continuum.
It is also believed that this is the first time anyone has demulsified a water/crude oil emulsion by the method of: (a) displacing one liquid from a surface of a bi-wetted solid disposed at a boundary of a water droplet and oil phase continuum with another liquid via reduction of liquid-solid interfacial tension at said boundary, and (b) displacing an indigenous crude oil surfactant film by another surfactant that permits water droplet coalescence and separation from said oil phase continuum.